export && import --exact fails in some cases

[Alexander Drozdov]

I have a changeset sequence which I should export in text format.
Some revisions in the sequence have extra properties such as "rebase_source=".
hg export don't include these properties to output file. So when I
import the sequence with '--exact --bypass' flags I get
'abort: patch is damaged or loses information' errors. I got that this happens
due to changeset ID changing.

So my question is how to export pathes with extra properties in text format?

Thank you!